The present invention relates to a recliner mechanism for a vehicle seat assembly and in particular to a manually actuated recliner mechanism having an infinitely variable lead screw with a cam actuated pawl for locking the recliner mechanism in a given position.
The seat back of the present invention has a recliner arm extending downwardly from the seat back pivot point. The lower end of the recliner arm carries a internally threaded nut that is threaded onto a fore and aft extending lead screw. Upon axial loading applied to the nut by the recliner arm, the lead screw will rotate about its axis translating the nut therealong. A locking gear is fixed to the lead screw and selectively engageable with a pawl to prevent rotation of the lead screw and therefore, pivoting of the seat back.
A rotating cam engages the pawl to hold the pawl in a lock position. Upon rotation of the cam, the pawl is moved out of engagement with the locking gear to permit the gear and the lead screw to rotate, causing translation of the nut along the screw, effecting angular adjustment of the seat back.
The lead screw is mounted for axial movement when axial forces above a predetermined value are applied to the screw by the nut. Upon such movement, one of the gear end faces will contact a confronting wall surface where friction between the gear and wall will prevent rotation of the gear and screw. As the axial force increase, so does the friction force. The friction force resisting rotation is more than the rotational force created by the helical threads of the screw. As a result, the mechanism is self locking under loading.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.